diff --git a/README.md b/README.md
index f8c3bb1..d6ac03d 100644
--- a/README.md
+++ b/README.md
@@ -2,9 +2,7 @@
 
 A Yunohost package for [Mattermost](http://www.mattermost.org/), an open-source, self-hosted alternative to Slack.
 
-## Build status
-
-See https://ci-apps.yunohost.org/jenkins/job/mattermost%20(Community)/ for checking current build status.
+[![Yunohost Build status](https://dash.yunohost.org/integration/mattermost.svg)](https://dash.yunohost.org/appci/app/mattermost)
 
 ## Requirements
 
@@ -16,17 +14,13 @@ Mattermost requires:
 
 ## Installing
 
+[![Install Mattermost with YunoHost](https://install-app.yunohost.org/install-with-yunohost.png)](https://install-app.yunohost.org/?app=mattermost)
+
 You can either :
 
-* Install from the Yunohost Admin web interface, by providing this URL: `https://github.com/YunoHost-Apps/mattermost_ynh`
-* Install from the command-line: `sudo yunohost app install https://github.com/YunoHost-Apps/mattermost_ynh`
-
-## Upgrading
-
-Mattermost upgrades tend to work only from one minor version to the other (3.0 to 3.1, 3.1 to 3.2, etc).
-
-**Important**: to upgrade from Mattermost 2.2, you will need an extra manual step.
-Run the upgrade from Yunohost, then follow [this guide](https://docs.mattermost.com/administration/upgrade.html).
+* Install by clicking the button above;
+* Install from the Yunohost Admin web interface, from the Community Apps list;
+* Install from the command-line: `sudo yunohost app install https://github.com/YunoHost-Apps/mattermost_ynh`.
 
 ## What works
 
diff --git a/Vagrantfile b/Vagrantfile
index a1dec32..ca9abb1 100644
--- a/Vagrantfile
+++ b/Vagrantfile
@@ -67,11 +67,6 @@ Vagrant.configure("2") do |config|
     # Install package_check
     if ! [ -f "$HOME/package_check/package_check.sh" ]; then
       git clone https://github.com/YunoHost/package_check
-      # Checkout our custom patches (until they get merged upstream)
-      cd package_check
-      git remote add kemenaran https://github.com/kemenaran/package_check.git
-      git fetch kemenaran
-      git checkout --track kemenaran/fixes
 
       # Fix LXC containers not being able to reach outside internet.
       # The default configuration is to detect the default gateway used
diff --git a/check_process b/check_process
index 5151a8f..43764ff 100644
--- a/check_process
+++ b/check_process
@@ -1,21 +1,25 @@
 ;; Mattermost
     ; Manifest
-        domain="ynhtests.local"    (DOMAIN)
+        domain="ynhtests.local" (DOMAIN)
         path="" (PATH)
-        language="fr"
+        admin_email="john@gmail.com"
+        admin_password="mattermost_password"
+        admin_locale="fr"
+        team_display_name="Mon équipe"
         is_public=1 (PUBLIC|public=1|private=0)
-        password="alpine"    (PASSWORD)
+        analytics=0
     ; Checks
         pkg_linter=1
         setup_root=1
-        setup_private=0
+        setup_private=1
         setup_public=1
         upgrade=1
         backup_restore=1
-        multi_instance=0
-        port_already_use=0 (XXXX)
+        multi_instance=1
+        port_already_use=1 (8085)
+        # Checks not supported yet
         change_url=0
-        # Tests not applicable
+        # Checks not applicable
         setup_sub_dir=0
         setup_nourl=0
         incorrect_path=0
@@ -23,7 +27,7 @@
     Level 1=auto
     Level 2=auto
     Level 3=auto
-    Level 4=0
+    Level 4=na
     Level 5=auto
     Level 6=auto
     Level 7=auto
diff --git a/conf/app.src b/conf/app.src
index 6606b69..b906bb9 100644
--- a/conf/app.src
+++ b/conf/app.src
@@ -1,6 +1,6 @@
-SOURCE_URL=https://releases.mattermost.com/4.4.2/mattermost-4.4.2-linux-amd64.tar.gz
-SOURCE_SUM=ba1648e5806239ce9071f5730eb712a6d0d9077fd9ecad37e85baeb08c1fa170
+SOURCE_URL=https://releases.mattermost.com/4.8.1/mattermost-4.8.1-linux-amd64.tar.gz
+SOURCE_SUM=3dac9f9bb4884cd83b8274c2bd7c32418f2535d3f9911cea845ac047ee2c7a82
 SOURCE_SUM_PRG=sha256sum
 SOURCE_FORMAT=tar.gz
 SOURCE_IN_SUBDIR=true
-SOURCE_FILENAME=mattermost-4.4.2-linux-amd64.tar.gz
+SOURCE_FILENAME=mattermost-4.8.1-linux-amd64.tar.gz
diff --git a/conf/nginx.conf b/conf/nginx.conf
index c11d89b..f2daff7 100644
--- a/conf/nginx.conf
+++ b/conf/nginx.conf
@@ -12,16 +12,11 @@ location ~ /api/v[0-9]+/(users/)?websocket$ {
     proxy_buffers 256 16k;
     proxy_buffer_size 16k;
     proxy_read_timeout 600s;
-    proxy_pass http://127.0.0.1:8065;
+    proxy_pass http://127.0.0.1:__PORT__;
 }
 
 location / {
     client_max_body_size 50M;
-    
-    if ($scheme = http) {
-        rewrite ^ https://$server_name$request_uri? permanent;
-        }
-    
     proxy_set_header Connection "";
     proxy_set_header Host $http_host;
     proxy_set_header X-Real-IP $remote_addr;
@@ -38,5 +33,9 @@ location / {
     #proxy_cache_min_uses 2;
     #proxy_cache_use_stale timeout;
     #proxy_cache_lock on;
-    proxy_pass http://127.0.0.1:8065;
+    proxy_pass http://127.0.0.1:__PORT__;
+    # Yunohost addition: redirect HTTP to HTTPS
+    if ($scheme = http) {
+        rewrite ^ https://$server_name$request_uri? permanent;
+    }
 }
diff --git a/conf/systemd.service b/conf/systemd.service
index 802d0bf..2bbde55 100644
--- a/conf/systemd.service
+++ b/conf/systemd.service
@@ -1,3 +1,6 @@
+# This file is managed by the Yunohost Mattermost package,
+# and will be overwritten on upgrade.
+
 [Unit]
 Description=Mattermost
 After=network.target
@@ -5,14 +8,9 @@ After=mysql.service
 Requires=mysql.service
 
 [Service]
-Type=simple
+Type=notify
 ExecStart=__FINALPATH__/bin/platform
-# HACK: Wait for Mattermost port to be open before declaring the service to be launched successfully.
-# This avoids to report the service as launched even when it crashes a few milliseconds after start.
-#
-# TODO: improve mattermost to send a STARTED notification, and
-# switch the service to 'Type=notify' instead.
-ExecStartPost=/usr/bin/timeout 10 /bin/sh -c 'while ! nc -z localhost 8065; do sleep 0.2; done'
+TimeoutStartSec=3600
 Restart=always
 RestartSec=10
 WorkingDirectory=__FINALPATH__
diff --git a/manifest.json b/manifest.json
index 61641df..d4a2ee7 100644
--- a/manifest.json
+++ b/manifest.json
@@ -7,12 +7,13 @@
         "fr": "Une alternative open-source et auto-hébergée à Slack"
     },
     "url": "http://www.mattermost.org/",
-    "license": "free",
+    "license": "GPL-3.0-only",
+    "version": "4.6.0-1",
     "maintainer": {
         "name": "pmorinerie",
         "email": "kemenaran@gmail.com"
     },
-    "multi_instance": false,
+    "multi_instance": true,
     "services": [
         "nginx"
     ],
@@ -31,19 +32,55 @@
                 "example": "domain.org"
             },
             {
-                "name": "public_site",
+                "name": "is_public",
+                "type": "boolean",
                 "ask": {
                     "en": "Can guest users access this chat?",
                     "fr": "Les utilisateurs non-enregistrés peuvent-ils accéder à ce chat ?"
                 },
-                "choices": ["Yes", "No"],
-                "default": "Yes"
+                "default": true
+            },
+            {
+                "name": "admin_email",
+                "ask": {
+                    "en": "Login email for the chat admin",
+                    "fr": "Adresse email de login pour l’administrateur du chat"
+                },
+                "example": "john@gmail.com",
+                "optional": false
+            },
+            {
+                "name": "admin_password",
+                "type": "password",
+                "ask": {
+                    "en": "Password for the chat admin",
+                    "fr": "Mot de passe pour l’administrateur du chat"
+                },
+                "optional": false
+            },
+            {
+                "name": "admin_locale",
+                "ask": {
+                    "en": "Choose the language of the chat for the admin",
+                    "fr": "Choissisez la langue utilisée pour l'administrateur"
+                },
+                "choices": ["en", "fr"],
+                "default": "en"
+            },
+            {
+                "name": "team_display_name",
+                "ask": {
+                    "en": "Choose a Team name",
+                    "fr": "Choisissez le nom de l’équipe"
+                },
+                "example": "Super Groupe",
+                "optional": false
             },
             {
                 "name": "analytics",
                 "type": "boolean",
                 "ask": {
-                    "en": "Do you want to allow Mattermost to send some telemetrics about your usage of this app?",
+                    "en": "Allow Mattermost to send some telemetrics about your usage of this app?",
                     "fr": "Autorisez-vous Mattermost à envoyer des informations anonymes sur votre usage de l’application ?"
                 },
                 "default": false
diff --git a/scripts/backup b/scripts/backup
index aa4bfe3..859f559 100755
--- a/scripts/backup
+++ b/scripts/backup
@@ -20,10 +20,9 @@ ynh_abort_if_errors
 app=$YNH_APP_INSTANCE_NAME
 
 final_path="/var/www/$app"
+data_path="/home/yunohost.app/$app"
 domain=$(ynh_app_setting_get $app domain)
 db_name="$app"
-default_backup_dir="${1}apps/$app"
-backup_dir=${backup_dir:-"$default_backup_dir"}
 
 #=================================================
 # STANDARD BACKUP STEPS
@@ -31,23 +30,29 @@ backup_dir=${backup_dir:-"$default_backup_dir"}
 # BACKUP THE APP MAIN DIR
 #=================================================
 
-ynh_backup "$final_path" "${backup_dir}$final_path"
+ynh_backup "$final_path"
+
+#=================================================
+# BACKUP THE APP DATA
+#=================================================
+
+ynh_backup "$data_path"
 
 #=================================================
 # BACKUP THE DATABASE
 #=================================================
 
 ynh_mysql_dump_db "$db_name" > db.sql
-ynh_backup "db.sql" "${backup_dir}/db.sql"
+ynh_backup "db.sql"
 
 #=================================================
 # BACKUP THE NGINX CONFIGURATION
 #=================================================
 
-ynh_backup "/etc/nginx/conf.d/$domain.d/$app.conf" "${backup_dir}/etc/nginx/conf.d/$domain.d/$app.conf"
+ynh_backup "/etc/nginx/conf.d/$domain.d/$app.conf"
 
 #=================================================
 # BACKUP SYSTEMD
 #=================================================
 
-ynh_backup "/etc/systemd/system/$app.service" "${backup_dir}/etc/systemd/system/$app.service"
+ynh_backup "/etc/systemd/system/$app.service"
diff --git a/scripts/install b/scripts/install
index 4da5910..621960d 100644
--- a/scripts/install
+++ b/scripts/install
@@ -21,7 +21,11 @@ ynh_abort_if_errors
 
 app=$YNH_APP_INSTANCE_NAME
 domain=$YNH_APP_ARG_DOMAIN
-is_public=$YNH_APP_ARG_PUBLIC_SITE
+is_public=$YNH_APP_ARG_IS_PUBLIC
+admin_email=$YNH_APP_ARG_ADMIN_EMAIL
+admin_password=$YNH_APP_ARG_ADMIN_PASSWORD
+admin_locale=$YNH_APP_ARG_ADMIN_LOCALE
+team_display_name=$YNH_APP_ARG_TEAM_DISPLAY_NAME
 analytics=$YNH_APP_ARG_ANALYTICS
 path_url="/"
 
@@ -55,15 +59,28 @@ then
     script_die "Mattermost requires MySQL 5.6 or higher, or MariaDB 10 or higher."
 fi
 
+#=================================================
+# FIND AN AVAILABLE PATH
+#=================================================
+
 # Normalize the url path syntax
 path_url=$(ynh_normalize_url_path $path_url)
 # Check web path availability
-ynh_webpath_available $domain $path_url
+ynh_webpath_available "$domain" "$path_url"
 # Register (book) web path
-ynh_webpath_register $app $domain $path_url
+ynh_webpath_register "$app" "$domain" "$path_url"
 # Store setting
 ynh_app_setting_set "$app" domain "$domain"
 
+#=================================================
+# FIND AN AVAILABLE PORT
+#=================================================
+
+# Find an available port
+port=$(ynh_find_port 8065)
+# Store setting
+ynh_app_setting_set "$app" port "$port"
+
 #=================================================
 # SET UP INSTALLATION VARIABLES
 #=================================================
@@ -77,19 +94,20 @@ logs_path="/var/log/$app"
 # CREATE A MYSQL DATABASE
 #=================================================
 
-db_name="mattermost"
+db_name="$app"
 db_user="mmuser"
 db_password=$(dd if=/dev/urandom bs=1 count=200 2> /dev/null | tr -c -d 'A-Za-z0-9' | sed -n 's/\(.\{24\}\).*/\1/p')
-ynh_mysql_create_db $db_name $db_user $db_password
-ynh_app_setting_set mattermost mysqlpwd "$db_password"
+ynh_mysql_create_db "$db_name" "$db_user" "$db_password"
+ynh_app_setting_set "$app" mysqlpwd "$db_password"
 
 #=================================================
 # CREATE USER FOR EMAIL NOTIFICATIONS
 #=================================================
 
-smtp_password=$(dd if=/dev/urandom bs=1 count=200 2> /dev/null | tr -c -d 'A-Za-z0-9' | sed -n 's/\(.\{24\}\).*/\1/p')
-sudo useradd -M --shell /bin/false -p $(openssl passwd -1 "$smtp_password") "mattermost"
-ynh_app_setting_set mattermost smtppwd "$smtp_password"
+mattermost_user="$app"
+mattermost_user_password=$(dd if=/dev/urandom bs=1 count=200 2> /dev/null | tr -c -d 'A-Za-z0-9' | sed -n 's/\(.\{24\}\).*/\1/p')
+sudo useradd -M --shell /bin/false -p $(openssl passwd -1 "$mattermost_user_password") "$mattermost_user"
+ynh_app_setting_set "$app" smtppwd "$mattermost_user_password"
 
 #=================================================
 # DOWNLOAD, CHECK AND UNPACK SOURCE
@@ -106,24 +124,25 @@ sudo mkdir -p "$logs_path"
 #=================================================
 
 # Configure Service Settings
-sudo sed -i "s|\"SiteURL\": \"\"|\"SiteURL\": \"https://${domain}${path_url}\"|g"      $final_path/config/config.json
+sudo sed -i "s|\"SiteURL\": \"\"|\"SiteURL\": \"https://${domain}${path_url}\"|g"          $final_path/config/config.json
+sudo sed -i "s|\"ListenAddress\": \".*\"|\"ListenAddress\": \"127.0.0.1:${port}\"|g"       $final_path/config/config.json
 # Configure the database connection
 db_connection_url="${db_user}:${db_password}@tcp(127.0.0.1:3306)/${db_name}?charset=utf8mb4,utf8"
-sudo sed -i "s|\"DataSource\": \".*\"|\"DataSource\": \"${db_connection_url}\"|g"      $final_path/config/config.json
+sudo sed -i "s|\"DataSource\": \".*\"|\"DataSource\": \"${db_connection_url}\"|g"          $final_path/config/config.json
 # Configure uploaded files directory
-sudo sed -i "s|\"Directory\": \"./data/\"|\"Directory\": \"${data_path}/\"|g"          $final_path/config/config.json
+sudo sed -i "s|\"Directory\": \"./data/\"|\"Directory\": \"${data_path}/\"|g"              $final_path/config/config.json
 # Configure SMTP account for sending email notifications
-sudo sed -i "s|\"SendEmailNotifications\": false|\"SendEmailNotifications\": true|g"   $final_path/config/config.json
-sudo sed -i "s|\"FeedbackName\": \"\"|\"FeedbackName\": \"Mattermost notification\"|g" $final_path/config/config.json
-sudo sed -i "s|\"FeedbackEmail\": \"\"|\"FeedbackEmail\": \"no-reply@${domain}\"|g"    $final_path/config/config.json
-sudo sed -i "s|\"SMTPUsername\": \"\"|\"SMTPUsername\": \"mattermost\"|g"              $final_path/config/config.json
-sudo sed -i "s|\"SMTPPassword\": \"\"|\"SMTPPassword\": \"${smtp_password}\"|g"        $final_path/config/config.json
-sudo sed -i "s|\"SMTPServer\": \"\"|\"SMTPServer\": \"localhost\"|g"                   $final_path/config/config.json
-sudo sed -i "s|\"SMTPPort\": \"\"|\"SMTPPort\": \"25\"|g"                              $final_path/config/config.json
+sudo sed -i "s|\"SendEmailNotifications\": false|\"SendEmailNotifications\": true|g"       $final_path/config/config.json
+sudo sed -i "s|\"FeedbackName\": \"\"|\"FeedbackName\": \"Mattermost notification\"|g"     $final_path/config/config.json
+sudo sed -i "s|\"FeedbackEmail\": \"\"|\"FeedbackEmail\": \"no-reply@${domain}\"|g"        $final_path/config/config.json
+sudo sed -i "s|\"SMTPUsername\": \"\"|\"SMTPUsername\": \"${mattermost_user}\"|g"          $final_path/config/config.json
+sudo sed -i "s|\"SMTPPassword\": \"\"|\"SMTPPassword\": \"${mattermost_user_password}\"|g" $final_path/config/config.json
+sudo sed -i "s|\"SMTPServer\": \"\"|\"SMTPServer\": \"localhost\"|g"                       $final_path/config/config.json
+sudo sed -i "s|\"SMTPPort\": \"\"|\"SMTPPort\": \"25\"|g"                                  $final_path/config/config.json
 # Disable Mattermost debug console by default
-sudo sed -i "s|\"EnableConsole\": true|\"EnableConsole\": false|g"                     $final_path/config/config.json
+sudo sed -i "s|\"EnableConsole\": true|\"EnableConsole\": false|g"                         $final_path/config/config.json
 # Configure log file location
-sudo sed -i "s|\"FileLocation\": \"\"|\"FileLocation\": \"$logs_path\"|g"              $final_path/config/config.json
+sudo sed -i "s|\"FileLocation\": \"\"|\"FileLocation\": \"$logs_path\"|g"                  $final_path/config/config.json
 # Configure analytics according to user choice
 if [ $analytics -eq 0 ]; then
     sudo sed -i "s|\"EnableDiagnostics\": true|\"EnableDiagnostics\": false|g"             $final_path/config/config.json
@@ -134,22 +153,20 @@ ynh_app_setting_set "$app" analytics "$analytics"
 # SECURE FILES AND DIRECTORIES
 #=================================================
 
-sudo chown -R mattermost:www-data "$final_path"
-sudo chown -R mattermost:www-data "$data_path"
-sudo chown -R mattermost:adm      "$logs_path"
+sudo chown -R "$mattermost_user:www-data" "$final_path"
+sudo chown -R "$mattermost_user:www-data" "$data_path"
+sudo chown -R "$mattermost_user:adm"      "$logs_path"
 
 #=================================================
 # NGINX CONFIGURATION
 #=================================================
 
-# Copy conf/nginx.conf to the correct location
 ynh_add_nginx_config
 
 #=================================================
 # SYSTEMD CONFIGURATION
 #=================================================
 
-# Create a dedicated systemd config
 ynh_add_systemd_config
 
 #=================================================
@@ -163,11 +180,11 @@ sudo yunohost service add "$app" --log "$logs_path/mattermost.log"
 #=================================================
 
 ynh_app_setting_set "$app" is_public "$is_public"
-if [ "$is_public" = "Yes" ];
-then
+
+if [[ $is_public == "1" ]]; then
+    # Make the app accessible to the public
     ynh_app_setting_set "$app" unprotected_uris "/"
 fi
-sudo yunohost app ssowatconf
 
 #=================================================
 # RELOAD NGINX
@@ -179,4 +196,21 @@ sudo systemctl reload nginx
 # START SERVER
 #=================================================
 
-sudo systemctl start mattermost
+sudo systemctl start "$app"
+
+#=================================================
+# CREATE ADMIN AND FIRST TEAM
+#=================================================
+
+admin_username=$(cut -d @ -f 1 <<< "$admin_email")
+team_name=$(echo "$team_display_name" | iconv -f utf8 -t ascii//TRANSLIT//IGNORE | sed -e 's/[^[:alnum:]]/-/g' | tr -s '-' | tr A-Z a-z)
+
+cd "$final_path/bin"
+sudo ./platform user create --username "$admin_username" --email "$admin_email" --password "$admin_password" --locale "$admin_locale" --system_admin
+sudo ./platform user verify "$admin_username"
+sudo ./platform team create --name "$team_name" --display_name "$team_display_name" --email "$admin_email"
+sudo ./platform team add "$team_name" "$admin_username"
+
+ynh_app_setting_set "$app" admin_email "$admin_email"
+ynh_app_setting_set "$app" admin_locale "$admin_locale"
+ynh_app_setting_set "$app" team_name "$team_name"
diff --git a/scripts/remove b/scripts/remove
index 2325037..988301f 100755
--- a/scripts/remove
+++ b/scripts/remove
@@ -14,9 +14,10 @@ source /usr/share/yunohost/helpers
 #=================================================
 
 app=$YNH_APP_INSTANCE_NAME
-domain=$(ynh_app_setting_get mattermost domain)
-db_name="mattermost"
+domain=$(ynh_app_setting_get $app domain)
+db_name="$app"
 db_user="mmuser"
+mattermost_user="$app"
 final_path="/var/www/$app"
 data_path="/home/yunohost.app/$app"
 logs_path="/var/log/$app"
@@ -76,4 +77,4 @@ sudo rm -rf "$logs_path"
 # REMOVE DEDICATED USER
 #=================================================
 
-ynh_system_user_delete "$app"
+ynh_system_user_delete "$mattermost_user"
diff --git a/scripts/restore b/scripts/restore
index bd4ef34..d1f4d44 100644
--- a/scripts/restore
+++ b/scripts/restore
@@ -27,6 +27,7 @@ data_path="/home/yunohost.app/$app"
 logs_path="/var/log/$app"
 db_name="$app"
 db_user="mmuser"
+mattermost_user="$app"
 
 #=================================================
 # CHECK IF THE APP CAN BE RESTORED
@@ -51,23 +52,29 @@ ynh_restore_file "/etc/nginx/conf.d/$domain.d/$app.conf"
 
 ynh_restore_file "$final_path"
 
+#=================================================
+# RESTORE THE APP DATA
+#=================================================
+
+ynh_restore_file "$data_path"
+
 #=================================================
 # RESTORE THE MYSQL DATABASE
 #=================================================
 
 db_pwd=$(ynh_app_setting_get $app mysqlpwd)
-ynh_mysql_setup_db $db_user $db_name $db_pwd
-ynh_mysql_connect_as $db_user $db_pwd $db_name < ./db.sql
+ynh_mysql_setup_db "$db_user" "$db_name" "$db_pwd"
+ynh_mysql_connect_as "$db_user" "$db_pwd" "$db_name" < ./db.sql
 
 #=================================================
 # RECREATE THE DEDICATED USER
 #=================================================
 
 # Create the dedicated user (if not existing)
-smtp_user="$app"
-if ! ynh_system_user_exists "$smtp_user"; then
-  smtp_password=$(ynh_app_setting_get $app smtp_password)
-  useradd -M --shell /bin/false -p $(openssl passwd -1 "$smtp_password") "$smtp_user"
+mattermost_user="$app"
+if ! ynh_system_user_exists "$mattermost_user"; then
+  mattermost_user_password=$(ynh_app_setting_get $app smtppwd)
+  useradd -M --shell /bin/false -p $(openssl passwd -1 "$mattermost_user_password") "$mattermost_user"
 fi
 
 #=================================================
@@ -75,21 +82,24 @@ fi
 #=================================================
 
 # Restore permissions on app files
-sudo chown -R mattermost:www-data "$final_path"
+sudo chown -R "$mattermost_user:www-data" "$final_path"
 
 mkdir -p "$data_path"
-sudo chown -R mattermost:www-data "$data_path"
+sudo chown -R "$mattermost_user:www-data" "$data_path"
 
 mkdir -p "$logs_path"
-sudo chown -R mattermost:adm "$logs_path"
+sudo chown -R "$mattermost_user:adm" "$logs_path"
 
 #=================================================
 # RESTORE SSOWAT
 #=================================================
 
-if [ "$is_public" = "Yes" ];
-then
+if [[ $is_public == "1" ]]; then
+  # Make the app accessible to the public
   ynh_app_setting_set "$app" unprotected_uris "/"
+else
+  # Remove the public access
+  ynh_app_setting_delete "$app" skipped_uris
 fi
 
 #=================================================
diff --git a/scripts/upgrade b/scripts/upgrade
index b09a62c..965f1f8 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -20,8 +20,10 @@ ynh_abort_if_errors
 #=================================================
 
 app=$YNH_APP_INSTANCE_NAME
-domain=$(ynh_app_setting_get mattermost domain)
-is_public=$(ynh_app_setting_get mattermost is_public)
+domain=$(ynh_app_setting_get $app domain)
+is_public=$(ynh_app_setting_get $app is_public)
+port=$(ynh_app_setting_get $app port)
+mattermost_user="$app"
 
 root_path="$(pwd)/.."
 final_path="/var/www/$app"
@@ -33,16 +35,32 @@ logs_path="/var/log/$app"
 #=================================================
 
 # Backup the current version of the app
-ynh_backup_before_upgrade
+# (NB: `tee` uses process substitution rather than a pipe,
+# to avoid spawning a subshell that would not save global
+# variables defined by `ynh_backup_before_upgrade`.)
+ynh_backup_before_upgrade > >(tee "upgrade.log")
+# Ensure the backup can be restored
+if grep -q "mattermost: Warning$" "upgrade.log"; then
+  can_restore_backup=false
+else
+  can_restore_backup=true
+fi
 
 # If the upgrade fails…
 ynh_clean_setup () {
-  # Stop attempting to restart the app
-  if $(sudo systemctl -q is-active "$app"); then
-    sudo systemctl stop "$app"
+  if [ "$can_restore_backup" = true ]; then
+    # Stop attempting to restart the app
+    if $(sudo systemctl -q is-active "$app"); then
+      sudo systemctl stop "$app"
+    fi
+    # Restore the backup
+    ynh_restore_upgradebackup
+  
+  else
+    # Backup restoration is not available:
+    # let's try at least to restart the server.
+    sudo systemctl start "$app"
   fi
-  # Restore the backup
-  ynh_restore_upgradebackup
 }
 
 # Exit if an error occurs during the execution of the script
@@ -57,7 +75,7 @@ if $(sudo systemctl -q is-active "$app"); then
   sudo systemctl stop "$app"
 fi
 
-# Legacy, for older versions of this app which used supervisor
+# Legacy, for previous versions of this app which used supervisor
 if [ -f "/etc/supervisor/conf.d/${app}.conf" ]; then
   sudo supervisorctl stop "$app"
   sudo rm -f "/etc/supervisor/conf.d/${app}.conf"
@@ -72,6 +90,24 @@ backup_config_file="/tmp/config.json"
 
 sudo cp -f "$config_file" "$backup_config_file"
 
+#=================================================
+# MIGRATE SETTINGS FROM PREVIOUS VERSIONS
+#=================================================
+
+# Convert is_public from "Yes"/"No" to 1 / 0
+if [[ $is_public == "Yes" ]]; then
+  is_public=1
+elif [[ $is_public == "No" ]]; then
+  is_public=0
+fi
+ynh_app_setting_set "$app" is_public "$is_public"
+
+# Save the port used if not present
+if ! [[ "$port" ]]; then
+  port=8065
+  ynh_app_setting_set "$app" port "$port"
+fi
+
 #=================================================
 # DOWNLOAD, CHECK AND UNPACK SOURCE
 #=================================================
@@ -123,9 +159,9 @@ fi
 # RESTORE FILE PERMISSIONS
 #=================================================
 
-sudo chown -R mattermost:www-data "$final_path"
-sudo chown -R mattermost:www-data "$data_path"
-sudo chown -R mattermost:adm      "$logs_path"
+sudo chown -R "$mattermost_user:www-data" "$final_path"
+sudo chown -R "$mattermost_user:www-data" "$data_path"
+sudo chown -R "$mattermost_user:adm"      "$logs_path"
 
 #=================================================
 # RELOAD NGINX